A recently published paper in The Journal of Bone and Joint Surgery Incorporated 2014; 96: 53-8 entitled “Evidence—Based Surgical Management of Spondylolisthesis Reduction Or Arthrodesis In Situ” reported “The role of reduction in the operative management of spondylolisthesis is controversial because of its potential complications, including neurologic deficits, prolonged operative time, and loss of reduction.” This study reported “The decision to correct high-grade slippage defects by reduction is still a controversial one. In an attempt to determine which patients should be treated with reduction, some authors have investigated the relationship between sagittal spinal parameters and pelvic morphology and orientation. Patients with high-grade spondylolisthesis could be classified on the basis of the orientation of the pelvis as having a “balanced” or unbalanced” pelvis. The balanced pelvis type of spondylolisthesis includes patients with low pelvic tilt and high sacral slope, whereas the unbalanced type includes patients with a retroverted pelvis having a high pelvic tilt and low sacral slope. On the basis of this classification, some authors suggest reduction of the deformity, restoring the spinopelvic balance, only in patients with an unbalanced pelvis, whereas arthrodesis in situ without correction would be preferred in patients with a balanced pelvis. Although reduction can potentially result in complications, complication rates in the present analysis did not differ between the reduction and arthrodesis in situ groups. On the other hand, reduction of a high-grade spondylolisthesis would improve overall spine biomechanics by correcting the local kyphotic deformity and reducing the vertebral slippage. We manage patients with high-grade spondylolisthesis by performing reduction under intraoperative neurophysiologic monitoring such as SSEPs combined with spontaneous electromyography. We usually perform a posterolateral or circumferential instrumented arthrodesis. In conclusion, we found no definite benefit of reduction over arthrodesis in situ except for a significantly lower rate of pseudarthrosis. Further adequately powered randomized trials with appropriate subjective and objective outcome measures are required to establish evidence-based surgical management of high-grade spondylolisthesis.”
The current surgical practice for low to medium grade spondylolisthesis reduction employs the use of pedicle screws with connective rods. Wherein the surgeon measures the amount of reduction required to realign the vertebrae and then uses the connecting rod to pull the upper vertebral body back causing a lever type action and placing the rod fastener into the tulip connection to fix the connections. As one can appreciate, this current best practice is at best an estimate of final reduction, due in part to a lack of control; the final results are typically a compromised approximation, but not a true alignment. Often this procedure of moving the adjacent vertebral bodies closer to alignment is a sufficient improvement to help the patient; however, this inability of the surgeon to precisely control the reduction is far from ideal. Furthermore, if the reduction achieved is less than satisfactory, the surgeon must start over loosening the rod and repositioning the pedicle screws, thus extending the surgical procedure.
The ideal reduction procedure would allow the surgeon to accomplish the reduction by controlling the movement in a consistent reliable and adjustable fashion so the exact optimal alignment is always achieved in the absence of predicting the preferred location, but rather controlling the movement to that exact location. Most importantly, this ability must occur in a timely fashion without unduly extending the surgical procedure.
The present invention as described herein accomplishes all these objectives and does so in typically less than 5 minutes added surgical time, most typically less than 4 minutes. Most advantageously, the system of the present invention is so accurate and reliable it virtually eliminates any need to redo the steps as there is no estimation made as to final placement, but rather a controlled movement to alignment which is fixed by the independent adjustment capability of the device in the hands of the surgeon aided by fluoroscopic vision.
These and other features of the system and its components afford new techniques in lumbar and thoracic spine surgery for use in a variety of indications as explained hereafter and shown in the attached drawings.